Communication system and communication method for improving signal processing efficiency

ABSTRACT

A communication system capable of improving signal processing efficiency even when a plurality of connections are established is provided. A communication system according to the present invention includes a user plane PGW ( 14 ) configured to connect to a PDN, a user plane SGW ( 12 ) configured to relay user plane data between the user plane PGW ( 14 ) and a base station ( 34 ), and a control plane SGW ( 30 ). Further, the communication system includes a control apparatus ( 32 ) configured to, when a plurality of connections are established for the communication terminal ( 36 ), transmit information indicating that the user plane PGW ( 14 ) and the user plane SGW ( 12 ) can be integrally configured to the control plane SGW ( 30 ) for each of the plurality of connections.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application of InternationalApplication No. PCT/JP2016/088813 entitled “COMMUNICATION SYSTEM ANDCOMMUNICATION METHOD,” filed on Dec. 27, 2016, which claims the benefitof the priority of Japanese Patent Application No. 2016-006030 filed onJan. 15, 2016, the disclosures of each of which are hereby incorporatedby reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a communication system, a controlapparatus, a communication method, and a program. In particular, thepresent disclosure relates to a communication system, a control device,a communication method, and a program for enabling a communicationterminal to establish a plurality of connections.

BACKGROUND ART

In 3GPP (3rd Generation Partnership Project) in which standards formobile communication systems have been drawn up, operations of nodeapparatuses and the like constituting a mobile network have beendefined. For example, Non-patent Literature 1 discloses an Attachprocess for registering a communication terminal such as a mobile phonein a network.

Specifically, Non-patent Literature 1 discloses, in Section 4.2, aconfiguration of a mobile network including a UE (User Equipment), aneNB (evolved Node B), an MME (Mobility Management Entity), an SGW(Serving Gateway), a PGW (Packet Data Network Gateway), and an HSS (HomeSubscriber Server). The UE is a general term for communication terminalssuch as mobile phones. The eNB is a base station that supports LTE (LongTerm Evolution) as a radio communication method. The MME is acommunication apparatus that performs mobility management of UEs,control of communication paths for user data in the mobile network, andso on. The SGW and PGW are gateways that relay user data. The SGW isdisposed in each predetermined area and accommodates UEs. The PGW is agateway connected to an external network and is disposed for eachservice to be provided (for each APN (Access Point Name)).

Further, Non-patent Literature 1 discloses, in Section 5.3.2, an Attachprocess. Further, it discloses, in Section 5.10, a process forestablishing a plurality of PDN (Packet Data Network) connections thatis performed when a UE receives a service related to a plurality ofAPNs. Establishment of a plurality of PDN connections may also bereferred to as Multiple-PDN Connections or the like. Regarding the PDNconnection, a PGW that establishes a connection is defined for each APN.Therefore, when a plurality of PDN connections are established, the UEestablishes a PDN connection with each of the plurality of PGWs throughthe eNB and the SGW.

Further, in order to improve efficiency of processing of signals thatare transmitted between an SGW and a PGW, there is a gateway apparatusin which an SGW and a PGW are integrally formed (Section 4.3.15a.2).

CITATION LIST Non Patent Literature

-   Non-patent Literature 1: 3GPP TS23.401 V13.5.0 (2015-12), Section    4.2, Section 4.3.15a.2, Section 5.3.2, Section 5.10

SUMMARY OF INVENTION Technical Problem

It has been desired to improve signal processing efficiency even in thecase disclosed in Non-patent Literature 1 in which a process forestablishing a plurality of PDN connections is performed.

An object of the present disclosure is to provide a communication systemand a communication method capable of further improving signalprocessing efficiency when at least one connection related to acommunication terminal is established.

Solution to Problem

A communication system according to the present disclosure includes: auser plane gateway configured to transmit user data related to acommunication terminal; and a control plane gateway separated from theuser plane gateway, in which the control plane gateway selects the userplane gateway based on location information and an APN (Access PointName) related to the communication terminal, and in the selected userplane gateway, a user plane SGW (Serving Gateway) and a user plane PGW(Packet Data Network Gateway) are integrally formed.

A communication method for a communication system according to thepresent disclosure includes: selecting, by a control plane gateway, auser plane gateway based on location information and an APN (AccessPoint Name) related to a communication terminal, the user plane gatewaybeing separated from the control plane gateway; and transmitting, by theselected user plane gateway, user data related to the communicationterminal, in which in the selected user plane gateway, a user plane SGW(Serving Gateway) and a user plane PGW (Packet Data Network Gateway) areintegrally formed.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide acommunication system and a communication method capable of furtherimproving signal processing efficiency when at least one connectionrelated to a communication terminal is established.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram of a communication system according toa first embodiment;

FIG. 2 is a diagram used for explaining an advantageous effect that isobtained when the communication system according to the first embodimentis used;

FIG. 3 is a configuration diagram of a communication system according toa second embodiment;

FIG. 4 is a configuration diagram of a communication system according toa third embodiment;

FIG. 5 is a configuration diagram of an MME according to the thirdembodiment;

FIG. 6 is a table showing information used for selecting an SGW-C/PGW-Capparatus according to the third embodiment;

FIG. 7 is a configuration diagram of an SGW-C according to the thirdembodiment;

FIG. 8 is a configuration diagram of a PGW-C according to the thirdembodiment;

FIG. 9 is a diagram showing a flow of a process for establishing aplurality of PDN connections according to the third embodiment;

FIG. 10 is a diagram showing a flow of a process for establishing aplurality of PDN connections according to the third embodiment;

FIG. 11 is a diagram showing a flow of a process for establishing aplurality of PDN connections according to a fourth embodiment;

FIG. 12 is a configuration diagram of a communication system accordingto a fifth embodiment;

FIG. 13 is a diagram showing a flow of a process for establishing aplurality of PDN connections according to a fifth embodiment;

FIG. 14 is a diagram showing a flow of a process for establishing aplurality of PDN connections according to a sixth embodiment;

FIG. 15 is a configuration diagram of a communication system accordingto a seventh embodiment; and

FIG. 16 is a configuration diagram of an MME, an SGW-C, and a PGW-Caccording to each embodiment.

DESCRIPTION OF EMBODIMENTS First Embodiment

Embodiments according to the present disclosure are describedhereinafter with reference to the drawings. Firstly, a configurationexample of a communication system according to a first embodiment of thepresent disclosure is described with reference to FIG. 1. Acommunication system shown in FIG. 1 includes an SGW-U (a user planeSGW) 12, a PGW-U (a user plane PGW) 14, an SGW-U 22, a PGW-U 24, anSGW-C (a control plane SGW) 30, a PGW-C (control plane PGW) 40, a PGW-C41, an MME 44, an eNB 48, and a UE 50. The communication system shown inFIG. 1 has a configuration in which a control plane and a user plane areseparated from each other. Further, the SGW-U and the PGW-U are formedas an integrated apparatus. The SGW-U and the PGW-U may also beexpressed as co-located. Paths indicated by solid lines between nodeapparatuses indicate a C-Plane (a control plane), and tunnel-like pathsindicated by using rectangles between node apparatuses indicate aU-Plane (a user plane).

Note that a gateway apparatus having functions of the SGW-U 12 and thePGW-U 14 may be used as a single apparatus for the user plane. A gatewayapparatus having functions of the SGW-U 22 and the PGW-U 24 may be usedas a single apparatus for the user plane. A control apparatus havingfunctions of the MME 44 and the SGW-C 30 may be used as a singleapparatus for the control plane. The eNB 48 may be a base stationapparatus and the UE 50 may be a communication terminal.

The communication system shown in FIG. 1 indicates that: a first PDN(Packet Data Network) connection is established by the UE 50, the eNB48, the SGW-U 12, and the PGW-U 14; and a second PDN connection isestablished by the UE 50, the eNB 48, the SGW-U 22, and the PGW-U 24.The first PDN connection established by the UE 50, the eNB 48, the SGW-U12, and the PGW-U 14 may be used for, for example, establishing anInternet connection. Further, the second PDN connection established bythe UE 50, the eNB 48, the SGW-U 22, and the PGW-U 24 may be used for,for example, establishing a connection to an IMS (IP MultimediaSubsystem).

The SGW-C 30 selects an SGW-U. For example, the SGW-C 30 selects theSGW-U 12 or 22 to establish a PDN connection related to the UE 50.Further, the SGW-C 30 may select a PGW-U and notify a PGW-C that it hasselected the PGW-U. For example, when the SGW-C 30 has selected thePGW-U 14 to establish a PDN connection related to the UE 50, it maynotify the PGW-C 40 that it has selected the PGW-U 14.

When the MME 44 selects an SGW-C and selects a PGW-C, it inquires of aDNS holding their identification information or address information (aDNS query). In this process, the MME 44 can also acquire informationindicating that the SGW-U and the PGW-U are co-located in addition tothe information on the SGW-C and the PGW-C acquired from the DNS. Notethat the DNS may also be referred to as a management apparatus.Specifically, in an extended DNS procedure, a PGW-C is selected whiletaking a TAI (Tracking Area Identity) into consideration. For example,when a PGW-C is found by using a combination of an APN (Access PointName) and a TAI, the SGW-U and the PGW-U can be co-located. The MME 44may acquire the APN from an HSS (Home Subscriber Server) and acquire theTAI from the eNB 48. The HSS manages subscriber information of the UE50. Alternatively, when a PGW-C is found by using a combination of anAPN (Access Point Name) and a TAI, and a canonical node name of theSGW-C matches a canonical node name of the PGW-C, the SGW-U and thePGW-U can be co-located. The canonical node name may be, for example,information indicating a partial domain name of an FQDN (Fully QualifiedDomain Name). The TAI is information for identifying a TA which is aunit area for paging a UE in an idle state.

When the MME 44 finds that the SGW-U and the PGW-U are co-located, itperforms the following process. In order to select an appropriate SGW-Uand a PGW-U, the MME 44 sends an indication flag to the SGW-C 30 and thePGW-C 40, or to the SGW-C 30 and the PGW-C 41 by using a Create SessionRequest message, and thereby informs them that the SGW-U and the PGW-Uare co-located.

Advantageous effects that are obtained by using a communication systemlike the one shown in FIG. 1, in which an SGW is separated into an SGW-Cand an SGW-U, and a PGW is separated into a PGW-C and a PGW-U, areexplained with reference to FIG. 2. FIG. 2 shows that while a co-locatedPGW 140 and an SGW 150 are used for a first PDN connection forestablishing an Internet connection, a PGW 141 that is not co-locatedwith an SGW 150 is used for a second PDN connection for establishing aconnection to an IMS. The PGW 140 used for establishing the Internetconnection differs from the PGW 141 used for connecting to the IMS.Therefore, the PGW 141, which is not co-located with the SGW 150, isused for the second PDN connection for connecting to the IMS.

In contrast to this, in the communication system shown in FIG. 1, theSGW-C 30 selected in the MME 44 is separated from the SGW-U 12 thattransmits/receives user plane data. The SGW-C 30 is a common SGW-C usedto control a plurality of PDN connections.

Specifically, as described above, in the communication system shown inFIG. 1, when a PDN connection is established, the MME 44 can find acollocated SGW-U and a PGW-U. Further, the MME 44 notifies the SGW-C 30that there are the co-located SGW-U and the PGW-U. Further, the SGW-C 30can select the SGW-U 12 and the PGW-U 14 used for the first PDNconnection, and select the SGW-U 22 and the PGW-U 24 used for the secondPDN connection. Note that the SGW-C 30 selects the co-located SGW-U andthe PGW for both of the first and second PDN connections. In this way,it is possible to use the co-located SGW-U and the PGW-U for both of thefirst and second PDN connections. As a result, even when a plurality ofPDN connections are established, it is possible to improve signalprocessing efficiency in the communication system.

Specifically, by the above-described configuration, the first embodimentcan reduce the number of tunnels in the communication system. Forexample, in FIG. 2 showing a configuration in which the presentdisclosure is not applied, two tunnels are required between the eNB andthe SGW and one tunnel is required between the SGW and the PGW. That is,three tunnels are required in total. In contrast to this, in FIG. 1, onetunnel is formed between the eNB 48 and the SGW-U 12, and one tunnel isformed between the eNB 48 and the SGW-U 22. That is, there are only twotunnels in total and hence, compared to FIG. 2, the number of tunnels isreduced by one.

Further, in FIG. 2, up to the second PDN on the IMS side, it isnecessary to set two paths, i.e., a path between the eNB 48 and the SGW150 and a path between the SGW 150 and the PGW 141. In contrast to this,in FIG. 1, only one path needs to be set between the eNB 48 and theSGW-U 22.

Further, in FIG. 2, in the second PDN connection on the IMS side, it isnecessary to convert a communication protocol between the SGW 150 andPGW 141 in order to perform tunneling control of the user plane. Incontrast to this, in FIG. 1, when the SGW-U 22 and the PGW-U 24 form anintegrated apparatus, it is unnecessary to convert a communicationprotocol between the SGW-U 22 and the PGW-U 24.

Further, in FIG. 2, it is necessary to perform a synchronization processbetween the SGW 150 and PGW 141. In contrast to this, in FIG. 1, whenthe SGW-U 22 and the PGW-U 24 form an integrated apparatus, it isunnecessary to perform a synchronization process between the SGW-U 22and the PGW-U 24.

Second Embodiment

A communication system shown in FIG. 3 includes an HSS 45, a PDN 1, aPDN 2, a gateway apparatus 10, a gateway apparatus 20, an SGW-C (acontrol plane SGW) 30, a control apparatus 32, a base station 34, and acommunication terminal 36.

The HSS 45, the gateway apparatus 10, the gateway apparatus 20, theSGW-C 30, the control apparatus 32, the base station 34, and thecommunication terminal 36 may be composed of a computer apparatus(s)that operates by having a processor execute a program stored in amemory.

The HSS 45, the gateway apparatus 10, the gateway apparatus 20, theSGW-C 30, and the control apparatus 32 are composed of an apparatus(s)constituting a core network. The PDNs 1 and 2 are packet networkslocated outside the core network. The PDNs 1 and 2 may be, for example,networks or the like managed by an IMS (IP Multimedia Subsystem) or anISP (Internet Service Provider) specified in the 3GPP.

The APN is information that indicates, when the communication terminal36 communicates with a PDN, a connection destination. That is, the APNis a name for identifying a PDN. By designating the APN, thecommunication terminal 36 can communicate with a desired PDN.

The communication terminal 36 is a computer apparatus having acommunication function. For example, the communication terminal 36 maybe a mobile phone terminal, a smartphone terminal, a tablet-typeterminal, or the like. Alternatively, the communication terminal 36 maybe an MTC (Machine Type Communication) terminal, a M2M (Machine toMachine) terminal, an IoT (Internet of Things) terminal, or the like,which autonomously perform communication without requiring a user'soperation

The base station 34 performs radio communication with the communicationterminal 36 by using a predetermined radio communication method. Thepredetermined radio communication method may be, for example, LTEspecified in the 3GPP, or a radio communication method called 3G, 2G, orthe like.

The gateway apparatus 10 is an apparatus in which the SGW-U (the userplane SGW) 12 and the PGW-U (the user plane PGW) 14 are formed as anintegrated apparatus (i.e., as a Collocated Gateway). In other words,the SGW-U 12 and the PGW-U 14 are co-located.

The PGW-U 14 connects to the PDN 1. The PGW-U 14 transmits user planedata related to the communication terminal 36 between the PGW-U 14 andthe PDN 1. The SGW-U 12 relays user plane data transmitted between thePGW-U 14 and the base station 34. The SGW-U 12 and the PGW-U 14 areformed as an integrated apparatus. Therefore, data transmission betweenthe SGW-U 12 and the PGW-U 14 is performed as an internal process in theapparatus. That is, when the SGW-U 12 is an apparatus different from thePGW-U 14, messages in the form of packet data are transmitted betweenthe SGW-U 12 and the PGW-U 14. However, when the SGW-U 12 and the PGW-U14 are formed as an integrated apparatus, messages in the form of packetdata are not transmitted between the apparatuses, i.e., between theSGW-U 12 and the PGW-U 14.

The gateway apparatus 20 is an apparatus in which the SGW-U 22 and thePGW-U 24 are formed as an integrated apparatus (i.e., as a CollocatedGateway).

The PGW-U 24 connects to the PDN 2. The PGW-U 24 transmits user planedata related to the communication terminal 36 between the PGW-U 24 andthe PDN 2. The SGW-U 22 relays user plane data transmitted between thePGW-U 24 and the base station 34. Note that the PGW-U 24 and the SGW-U22 have a configuration similar to that of the PGW-U 14 and the SGW-U12.

Meanwhile, the control plane SGW-C 30 is provided for common use by thegateway apparatus 10 and 20, and manages the SGW-Us 12 and 22. AlthoughFIG. 1 indicates that the SGW-C 30 manages the SGW-Us 12 and 22, theSGW-C 30 may manage three or more SGW-Us. The fact that the SGW-C 30manages the SGW-Us 12 and 22 may mean that, for example, the SGW-C 30selects an SGW-U with which the base station 34 will performcommunication between the SGW-Us 12 and 22. Alternatively, the fact thatthe SGW-C 30 manages the SGW-Us 12 and 22 may mean that, for example,the SGW-C 30 manages address information or the like related to theSGW-Us 12 and 22. The address information may be, for example, IPaddresses.

When the control apparatus 32 establishes a plurality of connections forthe communication terminal 36 by designating different APNs, it selectsthe SGW-C 30. Further, for each of the connections to be established,the control apparatus 32 transmits instruction information instructingto select a gateway apparatus in which a PGW-U and an SGW-U are formedas an integrated apparatus to the SGW-C 30.

User Plane Data related to the communication terminal 36 is transmittedto the gateway apparatus 10 or 20. Further, the user plane data relatedto the communication terminal 36 is received by the base station 34 fromthe gateway apparatus 10 or 20. The user plane data may also be referredto as User Data, U-Plane Data, or the like. In contrast to this, ControlPlane Data related to the communication terminal 36 is transmitted fromthe base station 34 to the control apparatus 32 and further transmittedfrom the control apparatus 32 to the SGW-C 30. Further, the controlplane data related to the communication terminal 36 is received by thebase station 34 from the SGW-C 30 through the control apparatus 32. Thecontrol plane data may also be referred to as control data, C-Planedata, or the like.

The fact that a plurality of connections are established means thatconnections that the communication terminal 36 uses to communicate withPDNs 1 and 2 are established. In order to establish a connection used tocommunicate with the PDN 1, the communication terminal 36 designates anAPN associated with the PDN 1. Further, in order to establish aconnection used to communicate with the PDN 2, the communicationterminal 36 designates an APN associated with the PDN 2. Further, theAPNs associated with the PDNs 1 and 2 may be provided from the HSS 45 tothe control apparatus 32 as subscriber data.

A connection is determined between the communication terminal 36 and thePDN 1 or 2. The connection may also be referred to as, for example, aPDN connection. Further, the PDN connection is composed of one or aplurality of communication bearers. By establishing a connection betweenthe communication terminal 36 and the PDN 1 or 2, a communication pathbetween the communication terminal 36 and the PDN 1 or 2 is determined.

The control apparatus 32 transmits instruction information to the SGW-C30. The instruction information instructs to select, when the controlapparatus 32 establishes, for example, a connection for which an APNassociated with the PDN 1 is designated, the gateway apparatus 10, inwhich the SGW-U and the PGW-U are formed as an integrated apparatus, andalso to select, when the control apparatus 32 establishes a connectionfor which an APN associated with the PDN 2 is designated, the gatewayapparatus 20.

As described above, when a plurality of connections for thecommunication terminal 36 are established by designating different APNs,the control apparatus 32 can transmit instruction informationinstructing to select a gateway apparatus in which a PGW-U and an SGW-Uare formed as an integrated apparatus to the SGW-C 30. That is, theSGW-C 30 is used as a common apparatus that controls a plurality ofconnections. Further, the SGW-C 30 and the control apparatus 32 may beformed as an integrated apparatus. By the above configuration, thesecond embodiment provides the same advantageous effects as those of thefirst embodiment. It is possible to reduce the number of tunnels in thecommunication system (specifically, the total number of tunnels betweenthe base station 34 and each of the gateway apparatuses 10 and 20 isreduced to two), and to reduce the number of paths to the PDNs(specifically, the number of paths between the base station 34 and eachof the gateway apparatuses 10 and 20 is reduced to one). Further, sinceuser plane data is processed in the gateway apparatus, the need for thecommunication protocol conversion and the synchronization process, whichwould otherwise be required between the SGW 150 and the PGW 141 as shownin FIG. 2, is eliminated.

Further, in the second embodiment, by separating the SGW-C thattransmits control plane data from the SGW-U, the connection establishedbetween the base station 34 and the PGW-U is separated from the SGW-C.As a result, even when the SGW-C 30 is used as a common apparatus thatcontrols a plurality of connections, a different SGW-U can be used foreach of the connections. Therefore, in each of the plurality ofconnections, it is possible to select the gateway apparatuses 10 and 20in each of which the SGW-U and the PGW-U are integrally configured, andestablish a connection between the base station 34 and the SGW-U 12 anda connection between the base station 34 and the SGW-U 22.

In this way, it is possible to use a gateway apparatus in each of theplurality of connections, and hence it is possible to preventunnecessary messages from being transmitted between the apparatuses,i.e., between the SGW-U and the PGW-U.

Third Embodiment

Next, a configuration example of a communication system according to asecond embodiment of the present disclosure is described with referenceto FIG. 4. In FIG. 4, the same symbols as those in FIGS. 1 and 3 areassigned to the same apparatuses as those in FIGS. 1 and 3. Acommunication system shown in FIG. 4 includes an HSS 45, a PDN 1, a PDN2, a gateway apparatus 10, a gateway apparatus 20, an SGW-C 30, a PGW-C40, a PGW-C 41, a PCRF (Policy Control and Charging Rules Function) 42,a PCRF 43, an MME (Mobility Management Entity) 44, a DNS (Domain NameSystem) 46, an eNB (evolved Node B) 48, and a UE (User Equipment) 50.

The UE 50 corresponds to the communication terminal 36 shown in FIG. 1.UE is used as a general term for mobile communication apparatuses in the3GPP.

The HSS 45 is a node apparatus specified in the 3GPP and managessubscriber data of the UE 50.

The MME 44 corresponds to the control apparatus 32 shown in FIG. 3. TheMME 44 is a node apparatus specified in the 3GPP and manages locationinformation of the UE 50. The MME 44 is a communication apparatus thatperforms mobility management of the UE 50, control of communicationpaths for user data in a mobile network, and so on. The locationinformation of the UE 50 may be, for example, a TA (Tracking Area) whichis a unit area for paging the UE in an idle state.

The eNB 48 corresponds to the base station 34 shown in FIG. 3. The eNB48 is a base station specified in the 3GPP and is a base station thatsupports LTE as a radio communication method.

The PGW-C 40 manages the PGW-U 14 and the PGW-C 41 manages the PGW-U 24.The fact that the PGW-C 40 manages the PGW-U 14 and the PGW-C 41 managesthe PGW-U 24 may mean that, for example, the PGW-C 40 and the PGW-C 41select PGW-Us which will connect with PDNs corresponding to designatedAPNs. Alternatively, the fact that the PGW-C 40 manages the PGW-U 14 andthe PGW-C 41 manages the PGW-U 24 may mean that, for example, the PGW-C40 manages address information or the like related to the PGW-U 14 andthe PGW-C 41 manages address information or the like related to thePGW-U 24.

While the SGW-C 30, the PGW-C 40, and the PGW-C 41 transmit controlplane data related to the UE 50, the SGW-U 12 and PGW-U 14, and theSGW-U 22 and PGW-U 24 transmit user plane data related to the UE 50.That is, in the communication system shown in FIG. 4, a communicationpath for control plane data related to the UE 50 is different from acommunication path for user plane data related to the UE 50.

The PCRF 42 transmits control plane data between the PCRF 42 and thePGW-C 40. The PCRF 43 transmits control plane data between the PCRF 43and the PGW-C 41. In communication with the PDN 1, the PCRF 42 performspolicy control of communication related to the UE 50, accounting controlrelated to the UE 50, or the like. In communication with the PDN 2, thePCRF 43 performs policy control of communication related to the UE 50,accounting control related to the UE 50, or the like.

In response to a request from the MME 44, the DNS 46 transmitsidentification information or address information of the SGW-C 30, thePGW-C 40, or the PGW-C 41 to the MME 44. The address information mayinclude IP address information.

By using the communication system shown in FIG. 4, the UE 50 cansimultaneously establish a PDN connection with the PDN 2 as well as withthe PDN 1. Further, when the UE 50 establishes a plurality of PDNconnections, the SGW-C 30 is used as the SGW-C that manages the SGW-U.Further, when the eNB 48 establishes PDN connections, the SGW-Us 12 and22 are used as the SGW-U.

That is, when the MME 44 establishes a plurality of PDN connections, itselects the SGW-C 30 as a common SGW-C.

When the communication path for control plane data is the same as thecommunication path for user plane data, that is, when the SGW-C 30 andSGW-U 12 are formed as an integral apparatus, the MME 44 selects, when aplurality of PDN connections are established, an apparatus in which theSGW-C 30 and SGW-U 12 are integrally formed as a common SGW for theplurality of PDN connections. Further, when the communication path forcontrol plane data differs from the communication path for user planedata as shown in FIG. 4, the MME 44 selects the SGW-C 30 as a commonSGW-C for a plurality of PDN connections as in the case where thecommunication path for control plane data is the same as thecommunication path for user plane data. By having the SGW-C or the PGW-Cselect the SGW-U that is used when PDN connections are established, whena plurality of PDN connections are established, an SGW-U is selected foreach of the PDN connections.

Reference points between components constituting the communicationsystem in FIG. 4 are described hereinafter. A reference point betweenthe UE 50 and the eNB 48 is defined as LTE-Uu. A reference point betweenthe eNB 48 and the MME 44 is defined as S1-MME. A reference pointbetween the MME 44 and the SGW-C 30 is defined as S11. A reference pointbetween the SGW-C 30 and the PGW-C 40 and that between the SGW-C 30 andthe PGW-C 41 are defined as S5/S8. A reference point between the PGW-C40 and the PCRF 42 and that between the PGW-C 41 and the PCRF 43 aredefined as Gx. Reference points between the eNB 48 and the SGW-U 12 andthat between the eNB 48 and the SGW-U 22 are defined as S1-U. Areference point between the PGW-U 14 and the PDN 1 and that between thePGW-U 24 and the PDN 2 are defined as SGi. A reference point between theMME 44 and the HSS 45 is defined as S6a.

Next, a configuration example of the MME 44 according to the secondembodiment of the present disclosure is described with reference to FIG.5. The MME 44 includes a communication unit 61, a selection unit 62, anda determination unit 63. The communication unit 61 may also be expressedas a transmitter-and-receiver. The communication unit 61, the selectionunit 62, and the determination unit 63 may be software or a module(s) bywhich processes are performed by having a processor execute a programstored in a memory. Alternatively, the communication unit 61, theselection unit 62, and the determination unit 63 may be hardware such asa circuit(s) or a chip(s).

The communication unit 61 communicates with the HSS 45, the eNB 48, theDNS 46, and the SGW-C 30. When the UE 50 establishes a plurality ofconnections by designating different APNs, the selection unit 62 selectsthe SGW-C. The selection unit 62 selects the SGW-C 30 that manages anSGW-U associated with a TAI (Tracking Area Identity) related to the UE50. For example, the selection unit 62 may transmit the TAI related tothe UE 50 to the DNS 46 through the communication unit 61 and receiveidentification information or address information related to the SGW-C30 that manages the SGW-Us 12 and 22 associated with the TAI related tothe UE 50 from the DNS 46.

Further, when the UE 50 establishes a plurality of connections bydesignating different APNs, the selection unit 62 selects a PGW-Caccording to the following criteria.

(Criterion 1) A PGW-C that manages a PGW-U associated with an APNdesignated by the UE 50.

(Criterion 2) A PGW-C that manages a PGW-U that constitutes, togetherwith an SGW-U associated with the TAI related to the UE 50, a gatewayapparatus as an integrated apparatus.

For example, assume that the PGW-U 14 is associated with an APNdesignated by the UE 50 and the SGW-Us 12 and 22 are present as TAIsrelated to the UE 50. In this case, the SGW-U 12 and the PGW-U 14constitute the gateway apparatus 10 as an integrated apparatus.Therefore, the selection unit 62 selects the PGW-C 40 that manages thePGW-U 14.

Further, assume that the PGW-U 24 is associated with an APN designatedby the UE 50 and the SGW-Us 12 and 22 are present as TAIs related to theUE 50. In this case, the SGW-U 22 and the PGW-U 24 constitute thegateway apparatus 20 as an integrated apparatus. Therefore, theselection unit 62 selects the PGW-C 40 that manages the PGW-U 24.

The selection unit 62 may transmit the TAI related to the UE 50 and theAPN designated by the UE 50 to the DNS 46 through the communication unit61 and receive identification information or address information relatedto a PGW-C that satisfies the Criteria 1 and 2 from the DNS 46.

The DNS 46 may determine whether or not the TAI and the APN transmittedform the MME 44 satisfy the Criteria 1 and 2 in accordance with a tableshown in FIG. 6. FIG. 6 indicates that as the DNS 46 is inquired ofabout PGW-C information based on information on a TAI_1 and an APN_1,the PGW-C 40 is output. Similarly, FIG. 6 indicates that as the DNS 46is inquired of about PGW-C information based on information on a TAI_1and an APN_2, the PGW-C 41 is output. Further, regarding the SGW-C, FIG.6 indicates that as the DNS 46 is inquired of about SGW-C informationbased on information on the TAI_1, the SGW-C 30 is output. In the nodeselection using the DNS shown here, when the SGW-C 30 and the PGW-C 40are selected, it is possible to select the gateway apparatus 10 as acommon user plane apparatus by the configuration shown in FIG. 4.

Specifically, the SGW-C 30 and the PGW-C 40 are output from the DNS 46to the MME 44 in the notation for domain names called FQDN (FullyQualified Domain Name). The MME 44 can select as a common user planeapparatus by comparing canonical node names indicating parts of theFQDNs of the SGW-C 30 and the PGW-C 40. Specifically, when a canonicalnode name of the SGW-C 30 matches a canonical node name of the PGW-C 40,or even when the canonical node name of the SGW-C 30 does not match thecanonical node name of the PGW-C 40, by using information indicating theconfiguration shown in FIG. 4 (e.g., information referred to as systemconfiguration information, configuration information, the like), it ispossible to select the gateway apparatus 10 as a common user planeapparatus.

Referring to FIG. 5 again, when the selection unit 62 has been able toreceive the identification information or the address informationrelated to the PGW-C from the DNS 46, the determination unit 63determines that there is a gateway apparatus in which an available SGW-Uand a PGW-U are formed as an integrated apparatus when a PDN connectionrelated to an APN designated by the UE 50 is established. When thedetermination unit 63 has determined that the gateway apparatus can beused when the connection is established, it transmits instructioninformation instructing to use the gateway apparatus in which the SGW-Uand the PGW-U are formed as an integrated apparatus to the selectedSGW-C 30 through the communication unit 61.

Next, a configuration example of the SGW-C 30 according to the secondembodiment of the present disclosure is described with reference to FIG.7. The SGW-C 30 includes a communication unit 71 and an instructioninformation determination unit 72. The communication unit 71 and theinstruction information determination unit 72 may be software or amodule(s) by which processes are performed by having a processor executea program stored in a memory. Alternatively, the communication unit 71and the instruction information determination unit 72 may be hardwaresuch as a circuit(s) or a chip(s).

The communication unit 71 communicates with the MME 44, the PGW-C 40,the SGW-U 12, and the SGW-U 22. The instruction informationdetermination unit 72 receives instruction information transmitted fromthe MME 44 through the communication unit 71. The instructioninformation transmitted from the MME 44 is information instructing touse a gateway apparatus in which the SGW-U and the PGW-U are formed asan integrated apparatus. Upon receiving the instruction informationtransmitted from the MME 44, the instruction information determinationunit 72 transmits the received instruction information to the PGW-C 40through the communication unit 71.

When the communication unit 71 receives an F-TEID (FullyQualified-Tunnel Endpoint Identifier) of a PGW-U for an S5/S8 referencepoint that the PGW-C 40 has selected based on the instructioninformation from the PGW-C 40, it stores the received F-TEID in a memoryor the like. Further, the communication unit 71 transmits the F-TEID ofthe PGW-U for the S5/S8 reference point selected by the PGW-C 40 to theMME 44. The F-TEID of the PGW-U for the S5/S8 reference point indicatesIP address information and a TEID of the PGW-U that are used when theSGW-U communicates with the PGW-U. The TEID is identificationinformation on the PGW-U 14 side of a tunnel set between the PGW-U 14and the SGW-U 12. In other words, the TEID of the PGW-U 14 isdestination information of a transmission destination that is used whenthe SGW-U 12 transmits user plane data related to the UE 50.

Next, a configuration example of the PGW-C 40 according to the secondembodiment of the present disclosure is described with reference to FIG.8. The configuration of the PGW-C 41 is similar to that of the PGW-C 40and hence a detailed description thereof is omitted. The PGW-C 40includes a communication unit 81, an instruction informationdetermination unit 82, and an apparatus selection unit 83. Thecommunication unit 81, the instruction information determination unit82, and the apparatus selection unit 83 may be software or a module(s)by which processes are performed by having a processor execute a programstored in a memory. Alternatively, the communication unit 81, theinstruction information determination unit 82, and the apparatusselection unit 83 may be hardware such as a circuit(s) or a chip(s).

The communication unit 81 communicates with the SGW-C 30, the PCRF 42,and the PGW-U 14. The instruction information determination unit 82receives instruction information transmitted from the SGW-C 30 throughthe communication unit 81. The instruction information transmitted fromthe SGW-C 30 is information instructing to use a gateway apparatus inwhich the SGW-U and the PGW-U are formed as an integrated apparatus.Upon receiving the instruction information transmitted from the SGW-C30, the instruction information determination unit 82 instructs theapparatus selection unit 83 to select the gateway apparatus.

When the apparatus selection unit 83 is instructed by the instructioninformation determination unit 82 to select the gateway apparatus, itselects a gateway apparatus composed of the PGW-U associated with theAPN designated by the UE 50 and the SGW-U associated with the TAIrelated to the UE 50.

The apparatus selection unit 83 may select a gateway apparatus by using,for example, information on the system configuration shown in FIG. 4(hereinafter referred to as configuration information). The apparatusselection unit 83 transmits the F-TEID of the PGW-U included in theselected gateway apparatus to the SGW-C 30 through the communicationunit 81.

Next, a flow of a process for establishing a plurality of PDNconnections according to the second embodiment of the present disclosureis described with reference to FIGS. 9 and 10. FIG. 9 shows a first PDNconnection establishing process and FIG. 10 shows a second PDNconnection establishing process. Further, FIG. 9 indicates that a PDNconnection is established in an Attach process for the UE 50. The Attachprocess is, for example, a process for registering (connecting) the UE50 in (to) a mobile network that is performed when a power supply of theUE 50 changes from an Off state to an On state.

Firstly, the UE 50 transmits an RRC message including an Attach Requestmessage to the eNB 48 by using an EMM (Evolved Mobility Management)protocol (S11). Next, the eNB 48 transmits an Initial UE Message to theMME 44 by using an S1AP (S1 Application Protocol) (S12). The Initial UEMessage includes the Attach Request message that the eNB 48 has receivedfrom the UE 50 and TAI information.

The MME 44 transmits an Update Location Request to the HSS 45 (S13).Next, the HSS 45 transmits subscriber data in which APN information isset to the MME 44 (S14).

Next, the MME 44 transmits a DNS Query message designating a TAI foridentifying a TA to which the eNB 48 belongs to the DNS 46 (S15). Forexample, the MME 44 sets a TAI_1 in the DNS Query message. Aftertransmitting the DNS Query message in the step S15, the MME 44 receivesa response message in which an SGW-C 30 associated with the designatedTAI_1 is set from the DNS 46. The SGW-C 30 manages the SGW-Us 12 and 22associated with the TAI_1.

Next, the MME 44 transmits a DNS Query message designating the TAI_1 andan APN_1 indicating an APN of a connection destination to the DNS 46(S16). After transmitting the DNS Query message in the step S16, the MME44 receives information indicating that there is a gateway apparatus inwhich an SGW-U associated with the TAI_1 and a PGW-U associated with theAPN_1 are integrally configured from the DNS 46. For example, when theMME 44 receives a response message in which the PGW-C 40 managing thePGW-U included in the gateway apparatus is set, it may determine thatthere is a gateway apparatus in which the SGW-U associated with theTAI_1 and the PGW-U associated with the APN_1 are integrally configured.In other words, when there is no gateway apparatus in which the SGW-Uassociated with the designated TAI and the PGW-U associated with thedesignated APN are integrally configured, the DNS 46 does not transmitthe response message in which the PGW-C is set to the MME 44.

Next, the MME 44 transmits a Create Session Request message in which aCollocated flag indicating that the SGW-U and the PGW-U can beintegrally configured (Collocation) is set together with the TAI_1 andthe APN_1 to the SGW-C 30 (S17). The MME 44 transmits the Create SessionRequest message to the SGW-C 30 by using GTPv2 (General Packet RadioService Tunneling Protocol version 2).

Next, when the Collocated flag is set in the Create Session Requestmessage transmitted from the MME 44, the SGW-C 30 transmits the receivedCreate Session Request message to the PGW-C 40 without selecting anSGW-U that communicates with the eNB 48 (S18). The PGW-C 40 selects theuser plane gateway apparatus 10 (the SGW-U and the PGW-U) according tothe Collocated flag set in the Create Session Request message.

For example, the PGW-C 40 selects the gateway apparatus 10 in which theSGW-U 12 associated with the TAI_1 and the PGW-U 14 associated with theAPN_1 are integrally configured by using the configuration informationshown in FIG. 4.

Next, when the PGW-C 40 selects the gateway apparatus 10, it transmits aCreate UP Session Request message to the PGW-U 14 included in thegateway apparatus 10 (S19). The PGW-C 40 sets an S1-U IP address whichis an IP address of the eNB 48, a TEID of the eNB 48, and an S5S8-U IPaddress in the Create UP Session Request message. Further, the PGW-C 40may set a TEID set in the PGW-C 40, QoS information related to the UE50, and the like in the Create UP Session Request message.

Next, the PGW-U 14 transmits the Create UP Session Request messagereceived from the PGW-C 40 to the SGW-U 12 (S20). Next, in response tothe Create UP Session Request message, the SGW-U 12 transmits a CreateUP Session Response message to the PGW-U 14 (S21). Note that the SGW-U12 and the PGW-U 14 are formed as an integrated apparatus in the gatewayapparatus 10. Therefore, the transmission of the Create UP SessionRequest message and the Create UP Session Response message between theSGW-U 12 and the PGW-U 14 is not performed as transmission of packetdata, but is performed as internal processes in the apparatus. Arrowsindicated by broken lines in the steps S20 and S21 indicate that theyare performed as internal processes in the apparatus. In this way, atunnel can be formed between the SGW-U 12 and the PGW-U 14.

Next, the PGW-U 14 transmits the Create UP Session Response message tothe PGW-C 40 as a response message to the Create UP Session Requestmessage transmitted in the step S19 (S22). Next, the PGW-C 40 transmitsthe Create Session Response message to the SGW-C 30 as a responsemessage to the Create Session Request message transmitted in the stepS18 (S23). The Create Session Response message includes the Collocatedflag and the F-TEIDs of the SGW-U 12 and the PGW-U 14 included in thegateway apparatus 10 selected by the PGW-C 40. Note that a protocolother than the GTP protocol may be used for the above-described CreateUP Session Request message and the Create UP Session Response message.

Next, the SGW-C 30 transmits a Create Session Response message in whichthe F-TEID of the SGW-U 12 is set to the MME 44 (S24). An Attach processperformed in the step S24 and subsequent steps is similar to an Attachprocess specified in Non-patent Literature 1 and hence a detaileddescription thereof is omitted. By performing the Attach process shownin FIG. 9, a PDN connection is established between the UE 50 and thePGW-U 14.

Next, a flow of a second PDN connection establishing process isdescribed with reference to FIG. 10. Firstly, the UE 50 transmits an RRCmessage including a PDN Connectivity Request message to the eNB 48 byusing an ESM (Evolved Session Management) protocol (S31). An APN is setin the PDN Connectivity Request message. Next, the eNB 48 transmits anUplink NAS (Non Access Stratum) Transport message including the PDNConnectivity Request message to the MME 44 by using an S1AP (S32). TheUplink NAS Transport includes the PDN Connectivity Request message thatthe eNB 48 has received from the UE 50. After that, processes similar tothose in the steps S13 to S24 shown in FIG. 9 are performed. When thesteps S13 to S24 shown in FIG. 9 are performed in the second PDNconnection establishing process, a TAI_1 and an APN_2 shown in FIG. 4are used as parameters set in the Create Session Request message.Therefore, the PGW-C 41 selects the user plane gateway apparatus 20 (theSGW-U and the PGW-U). In this way, when the processes shown in FIG. 10are completed, a PDN connection is established between the UE 50 and thePGW-U 24. As a result, the first PDN connection is established betweenthe UE 50 and the gateway apparatus 10, and the second PDN connection isestablished between the UE 50 and the gateway apparatus 20. Note thatwhen PDN connections for three or more APNs are established, they can beestablished by repeating processes similar to those shown in FIG. 10.

As described above, in the third embodiment according to the presentdisclosure, the SGW is separated into a SGW-C and a SGW-U, and the PGWis separated into a PGW-C and a PGW-U. By doing so, a communication pathfor control plane data and a communication path for user plane data areseparated from each other. Further, in the third embodiment according tothe present disclosure, a gateway apparatus in which an SGW-U and aPGW-U both of which transmit/receive user plane data are integrallyconfigured is used. When a plurality of PDN connections are established,the PGW-C selects a gateway apparatus used for a respective one of thePDN connections. By doing so, it is possible to perform transmission ofmessages between the SGW-U and the PGW-U as internal processes in thegateway apparatus.

Further, in FIG. 9, although the MME 44 sets the TAI_1 in the DNS Querymessage and transmits the DNS Query message in the step S16, it may setonly the APN designated by the UE 50 without setting the TAI_1. In sucha case, the DNS 46 transmits a response message in which the PGW-Cassociated only with the APN is set to the MME 44. The MME 44 receivesthe response message in which the PGW-C is set. However, depending onthe configuration, the MME 44 may be able to determine whether there isa gateway apparatus in which the SGW-U and the PGW-U are integrallyconfigured.

Further, even when the MME 44 cannot determine whether there is agateway apparatus in which the SGW-U and the PGW-U are integrallyconfigured, the MME 44 transmits the Create Session Request message inwhich the Collocated flag is set to the SGW-C 30. That is, when the MME44 sets only the APN in the DNS Query message without setting the TAIand transmits the DNS Query message to the DNS 46, the MME 44 transmitsthe Create Session Request message in which the Collocated flag is setto the SGW-C 30 without determining whether or not there is the gatewayapparatus. The SGW-C 30 transmits the received Create Session Requestmessage to the PGW-C 40. When there is a gateway apparatus in which theSGW-U and the PGW-U associated with the APN and the TAI included in theCreate Session Request message are integrally configured, the PGW-C 40performs processes similar to those in the step S19 and subsequent stepsshown in FIG. 9. For example, the PGW-C 40 may determine whether or notthere is a gateway apparatus in which the SGW-U and the PGW-U associatedwith the APN and the TAI included in the Create Session Request messageare integrally configured by using the configuration information shownin FIG. 4. When there is no gateway apparatus in which the SGW-U and thePGW-U associated with the APN and the TAI included in the Create SessionRequest message are integrally configured, the PGW-C 40 may transmit anerror message to the SGW-C 30.

Fourth Embodiment

Next, a flow of an Attach process that is performed when a process forestablishing a plurality of PDN connections according to a thirdembodiment is performed is described with reference to FIG. 11. StepsS41 to S47 in FIG. 11 are similar to the steps S11 to S17 in FIG. 9, andhence detailed descriptions thereof are omitted.

When a Collocated flag is set in a Create Session Request messagetransmitted from the MME 44 in the step S47, the SGW-C 30 selects agateway apparatus that transmits/receives user plane data by using theTAI and APN information and the like included in the Create SessionRequest message. A fourth embodiment is different from the thirdembodiment in that while the SGW-C 30 selects a gateway apparatus in thefourth embodiment, the PGW-C 40 selects a gateway apparatus in the thirdembodiment.

For example, the SGW-C 30 selects the gateway apparatus 10 in which theSGW-U 12 associated with the TAI_1 and the PGW-U 14 associated with theAPN_1 are integrally configured by using the configuration informationshown in FIG. 4.

Next, when the SGW-C 30 selects the gateway apparatus 10, it transmits aCreate UP Session Request message to the SGW-U 12 included in thegateway apparatus 10 (S48). The SGW-C 30 sets an S1-U IP address whichis an IP address of the eNB 48, a TEID of the eNB 48, and an S5S8-U IPaddress in the Create UP Session Request message. Further, the SGW-C 30may set a TEID set in the SGW-C 30, QoS information related to the UE50, and the like in the Create UP Session Request message.

Next, the SGW-U 12 transmits the Create UP Session Request messagereceived from the SGW-C 30 to the PGW-U 14 (S49). Next, in response tothe Create UP Session Request message, the PGW-U 14 transmits a CreateUP Session Response message to the SGW-U 12 (S50). Note that the SGW-U12 and the PGW-U 14 are formed as an integrated apparatus in the gatewayapparatus 10. Therefore, the transmission of the Create UP SessionRequest message and the Create UP Session Response message between theSGW-U 12 and the PGW-U 14 is not performed as transmission of packetdata, but is performed as internal processes in the apparatus. Arrowsindicated by broken lines in the steps S49 and S50 indicate that theyare performed as internal processes in the apparatus. In this way, atunnel can be formed between the SGW-U 12 and the PGW-U 14.

Next, the SGW-U 12 transmits a Create UP Session Response messageincluding SGW-U information (F-TEID) and PGW-U information (F-TEID) tothe SGW-C 30 as a response message to the Create UP Session Requestmessage transmitted in the step S48 (S51). Next, the SGW-C 30 transmitsa Create Session Request message to the PGW-C 40 by using a GTPv2protocol (S52). The Create Session Request message includes a Collocatedflag and the PGW-U information (F-TEID) of the PGW-U 14 included in theselected gateway apparatus 10. Next, the PGW-C 40 transmits a CreateSession Response message to the SGW-C 30 (S53). The Create SessionResponse message includes the Collocated flag and the F-TEID of thePGW-U 14. Note that a protocol other than the GTP protocol may be usedfor the above-described Create UP Session Request message and the CreateUP Session Response message.

Next, the SGW-C 30 transmits a Create Session Response message to theMME 44 as a response message to the Create Session Request messagetransmitted in the step S47 (S54). An Attach process in the step S54 andsubsequent steps is similar to an Attach process specified in Non-patentLiterature 1 and hence a detailed description thereof is omitted.

Further, a second PDN connection establishing process is similar to thatshown in FIG. 10. Further, in a step S32 and subsequent steps in FIG.10, processes similar to those in the steps S43 to S54 in FIG. 11 areperformed. When the steps S43 to S54 shown in FIG. 11 are performed inthe second PDN connection establishing process, a TAI_1 and an APN_2shown in FIG. 6 are used as parameters set in the Create Session Requestmessage. Therefore, the SGW-C 30 selects the gateway apparatus 20.

As described above, in the third embodiment according to the presentdisclosure, the SGW is separated into a SGW-C and a SGW-U, and the PGWis separated into a PGW-C and a PGW-U. By doing so, a communication pathfor control plane data and a communication path for user plane data areseparated from each other. Further, in the third embodiment according tothe present disclosure, a gateway apparatus in which an SGW-U and aPGW-U are integrally configured is used. When a plurality of PDNconnections are established, the SGW-C selects a gateway apparatus usedfor a respective one of the PDN connections. By doing so, it is possibleto perform transmission of messages between the SGW-U and the PGW-U asinternal processes in the gateway apparatus.

Further, in FIG. 11, although the MME 44 sets the TAI_1 in the DNS Querymessage and transmits the DNS Query message in the step S46, it may setonly the APN designated by the UE 50 without setting the TAI_1. In sucha case, the DNS 46 transmits a response message in which the PGW-Cassociated only with the APN is set to the MME 44. The MME 44 receivesthe response message in which the PGW-C is set. However, depending onthe configuration, the MME 44 may be able to determine whether there isa gateway apparatus in which the SGW-U and the PGW-U are integrallyconfigured.

Further, even when the MME 44 cannot determine whether there is agateway apparatus in which the SGW-U and the PGW-U are integrallyconfigured, the MME 44 transmits the Create Session Request message inwhich the Collocated flag is set to the SGW-C 30. That is, when the MME44 sets only the APN in the DNS Query message without setting the TAIand transmits the DNS Query message to the DNS 46, the MME 44 transmitsthe Create Session Request message in which the Collocated flag is setto the SGW-C 30 without determining whether or not there is the gatewayapparatus. When there is a gateway apparatus in which the SGW-U and thePGW-U associated with the APN and the TAI included in the Create SessionRequest message are integrally configured, the SGW-C 30 performsprocesses similar to those in the step S48 and subsequent steps shown inFIG. 11. For example, the SGW-C 30 may determine whether or not there isa gateway apparatus in which the SGW-U and the PGW-U associated with theAPN and the TAI included in the Create Session Request message areintegrally configured by using the configuration information shown inFIG. 4. When there is no gateway apparatus in which the SGW-U and thePGW-U associated with the APN and the TAI included in the Create SessionRequest message are integrally configured, the SGW-C 30 may transmit anerror message to the MME 44.

Fifth Embodiment

Next, a configuration example of a communication system according to afourth embodiment of the present disclosure is described with referenceto FIG. 12. In FIG. 12, the same symbols as those in FIG. 4 are assignedto the same apparatuses as those in FIG. 4. Further, detaileddescriptions of the same apparatuses as those in FIG. 4 are omitted.

A communication system shown in FIG. 10 includes an HSS 45, a UE 50, aUTRAN (Universal Terrestrial Radio Network) 90, a DNS 46, a PCRF 42, aPCRF 43, an SGSN-C(Serving GPRS Support Node-C) 91, a GGSN-C (GatewayGPRS Support Node-C) 92, a GGSN-C 97, a gateway apparatus 110, a gatewayapparatus 120, a PDN 101, and a PDN 102.

The UTRAN 90 is a network including a base station corresponding to thebase station 34 shown in FIG. 3. The UTRAN 90 is a network including abase station specified in the 3GPP, and is a network including a basestation that supports a radio communication method defined as 3G.

The SGSN-C 91 corresponds to the SGW-C 30 and the MME 44 shown in FIG.4, and the GGSN-C 92 corresponds to the PGW-C 40 shown in FIG. 4.Further, the GGSN-C 97 corresponds to the PGW-C 41 shown in FIG. 4.

The gateway apparatus 110 includes an SGSN-U 93 and a GGSN-U 94, and theSGSN-U 93 and the GGSN-U 94 are formed as an integrated apparatus(Collocated Gateway). Further, the gateway apparatus 120 includes anSGSN-U 95 and a GGSN-U 96, and the SGSN-U 95 and the GGSN-U 96 areformed as an integrated apparatus. In other words, the SGSN-U 93 and theGGSN-U 94 are co-located, and the SGSN-U 95 and the GGSN-U 96 areco-located.

The SGSN-U 93 corresponds to the SGW-U 12 shown in FIG. 4, and theGGSN-U 94 corresponds to the PGW-U 14 shown in FIG. 4. Further, theSGSN-U 95 corresponds to the SGW-U 22 in FIG. 4, and the GGSN-U 96corresponds to the PGW-U 24 in FIG. 4.

While the SGSN-C 91, the GGSN-C 92, and the GGSN-C 97 transmit controlplane data related to the UE 50, the SGSN-U 93 and the GGSN-U 94, andthe SGSN-U 95 and the GGSN-U 96 transmit user plane data related to theUE 50. That is, in the communication system shown in FIG. 12, acommunication path for control plane data related to the UE 50 isdifferent from a communication path for user plane data related to theUE 50.

In response to a request from the SGSN-C 91, the DNS 46 transmitsidentification information or address information of the GGSN-C 92 orthe GGSN-C 97 to the SGSN-C 91. The address information may include IPaddress information.

By using the communication system shown in FIG. 12, the UE 50 cansimultaneously establish a PDN connection with the PDN 102 as well aswith the PDN 101. Further, when the UE 50 establishes a plurality of PDNconnections, the SGSN-C 91 is used as the SGSN-C that manages theSGSN-U. Further, the SGSN-Us 93 and 95 are used as the SGSN-U thatestablishes a PDN connection.

That is, when the UTRAN 90 establishes a plurality of PDN connections,it selects the SGSN-C 91 as a common SGSN-C.

Reference points between components constituting the communicationsystem in FIG. 12 are described hereinafter. A reference point betweenthe UE 50 and the UTRAN 90 is defined as Uu. A reference point betweenthe UTRAN 90 and the SGSN-C 91 is defined as Iu. A reference pointbetween the SGSN-C 91 and the GGSN-C 92 and that between the SGSN-C 91and the GGSN-C 97 is defined as Gn/Gp. A reference point between theGGSN-C 92 and the PCRF 42 and that between the GGSN-C 97 and the PCRF 43is defined as Gx. A reference point between the GGSN-U 94 and the PDN 1and that between the GGSN-U 96 and PDN 2 is defined as Gi.

Next, a flow of process for establishing a plurality of PDN connectionsaccording to the fourth embodiment of the present disclosure isdescribed with reference to FIG. 13. FIG. 13 shows a first PDNconnection establishing process. Further, a second PDN connectionestablishing process is similar to that shown in FIG. 13. That is, whentwo PDN connections are established, the process shown in FIG. 13 isrepeated twice.

Firstly, the UE 50 transmits an Activate PDP Context Request message tothe SGSN-C 91 by using a GMM (GPRS Mobility Management) protocol (S61).

The SGSN-C 91 transmits an Update Location Request to the HSS 45 (S62).Next, the HSS 45 transmits subscriber data in which APN information isset to the SGSN-C 91 (S63).

Next, the SGSN-C 91 transmits a DNS Query message designating an RAI(Routing Area Identity) for identifying an RA (Routing Area) to whichthe UTRAN 90 belongs and an APN to which the UE 50 will connect to theDNS 46 (S64). After transmitting the DNS Query message in the step S64,the SGSN-C 91 receives information indicating that there is a gatewayapparatus in which an SGSN-U associated with the RAI and a GGSN-Uassociated with the APN are integrally configured from the DNS 46. Forexample, when the SGSN-C 91 receives a response message in which theGGSN-C managing the GGSN-U included in the gateway apparatus is set, itmay determine that there is a gateway apparatus in which the SGSN-Uassociated with the RAI and the GGSN-U associated with the APN areintegrally configured. In other words, when there is no gatewayapparatus in which the SGSN-U associated with the designated RAI and theGGSN-U associated with the designated APN are integrally configured, theDNS 46 does not transmit the response message in which the GGSN-C is setto the SGSN-C 91.

Next, when the SGSN-C 91 determines that there is the gateway apparatus,it transmits a Create PDP Context Request message in which a Collocatedflag indicating that the SGSN-U and the GGSN-U can be integrallyconfigured (Collocation) is set together with the RAI and the APN to theGGSN-C 92 without selecting the SGSN-U (S65). The SGSN-C 91 transmitsthe Create PDP Context Request message to the GGSN-C 92 by using GTPv1(General Packet Radio Service Tunneling Protocol version 1).

The GGSN-C 92 selects the user plane gateway apparatus 110 (the SGSN-Uand the GGSN-U) according to the Collocated flag set in the Create PDPContext Request message by using the RAI and APN information and thelike included in the Create PDP Context Request message.

Next, when the GGSN-C 92 selects the gateway apparatus 110, it transmitsa Create UP Session Request message to the GGSN-U 94 included in thegateway apparatus 110 (S66).

Next, the GGSN-U 94 transmits the Create UP Session Request messagereceived from the GGSN-C 92 to the SGSN-U 93 (S67). Next, in response tothe Create UP Session Request message, the SGSN-U 93 transmits a CreateUP Session Response message to the GGSN-U 94 (S68). Note that the SGSN-U93 and the GGSN-U 94 are formed as an integrated apparatus in thegateway apparatus 110. Therefore, the transmission of the Create UPSession Request message and the Create UP Session Response messagebetween the SGSN-U 93 and the GGSN-U 94 is not performed as transmissionof packet data, but is performed as internal processes in the apparatus.Arrows indicated by broken lines in the steps S67 and S68 indicate thatthey are performed as internal processes in the apparatus. In this way,a tunnel can be formed between the SGSN-U 93 and the GGSN-U 94.

Next, the GGSN-U 94 transmits a Create UP Session Response message tothe GGSN-C 92 as a response message to the Create UP Session Requestmessage transmitted in the step S66 (S69). Note that a protocol otherthan the GTP protocol may be used for the above-described Create UPSession Request message and the Create UP Session Response message.

Next, the GGSN-C 92 transmits a Create PDP Context Response message tothe SGSN-C 91 as a response message to the Create PDP Context Requestmessage transmitted in the step S65 (S70).

An Attach process in the step S70 and subsequent steps is similar to anAttach process specified in Non-patent Literature 1 and hence a detaileddescription thereof is omitted.

Further, in FIG. 13, although the SGSN-C 91 sets the RAI in the DNSQuery message and transmits the DNS Query message in the step S64, itmay set only the APN designated by the UE 50 without setting the RAI. Insuch a case, the DNS 46 transmits a response message in which the GGSN-C92 associated only with the APN is set to the SGSN-C 91. The SGSN-C 91receives the response message in which the GGSN-C 92 is set. However,depending on the configuration, the SGSN-C 91 may be able to determinewhether there is a gateway apparatus in which the SGSN-U and the GGSN-Uare integrally configured.

Further, even when the SGSN-C 91 cannot determine whether there is agateway apparatus in which the SGSN-U and the GGSN-U are integrallyconfigured, the SGSN-C 91 transmits the Create PDP Context Requestmessage in which the Collocated flag is set to the GGSN-C 92. That is,when the SGSN-C 91 sets only the APN in the DNS Query message withoutsetting the RAI and transmits the DNS Query message to the DNS 46, theSGSN-C 91 transmits the Create PDP Context Request message in which theCollocated flag is set to the GGSN-C 92 without determining whether ornot there is the gateway apparatus. The SGSN-C 91 transmits the receivedCreate PDP Context Request message to the GGSN-C 92. When there is agateway apparatus in which the SGSN-U and the GGSN-U associated with theAPN and the RAI included in the Create PDP Context Request message areintegrally configured, the GGSN-C 92 performs processes similar to thosein the step S66 and subsequent steps shown in FIG. 13. For example, theGGSN-C 92 may determine whether or not there is a gateway apparatus inwhich the SGSN-U and the GGSN-U associated with the APN and the RAIincluded in the Create PDP Context Request message are integrallyconfigured by using the configuration information shown in FIG. 12. Whenthere is no gateway apparatus in which the SGSN-U and the GGSN-Uassociated with the APN and the RAI included in the Create PDP ContextRequest message are integrally configured, the GGSN-C 92 may transmit anerror message to the SGSN-C 91.

Sixth Embodiment

Next, a flow of process for establishing a plurality of PDN connectionsaccording to a fifth embodiment of the present disclosure is describedwith reference to FIG. 14. FIG. 14 shows a first PDN connectionestablishing process. Further, a second PDN connection establishingprocess is similar to that shown in FIG. 14. That is, when two PDNconnections are established, the process shown in FIG. 14 is repeatedtwice.

Steps S71 to S74 are similar to the steps S61 to S64 in FIG. 13, andhence detailed descriptions thereof are omitted.

Next, when the SGSN-C 91 determines that there is a gateway apparatus,it selects the gateway apparatus. Upon selecting the gateway apparatus110, the SGSN-C 91 transmits a Create UP Session Request message to theSGSN-U 93 included in the gateway apparatus 110 (S75). The sixthembodiment is different from the fifth embodiment in that while theSGSN-C 91 selects the gateway apparatus in the sixth embodiment, theGGSN-C 92 selects the gateway apparatus in the fifth embodiment.

Next, the SGSN-U 93 transmits the Create UP Session Request messagereceived from the SGSN-C 91 to the GGSN-U 94 (S76). Next, in response tothe Create UP Session Request message, the GGSN-U 94 transmits a CreateUP Session Response message to the SGSN-U 93 (S77). Note that the SGSN-U93 and the GGSN-U 94 are formed as an integrated apparatus in thegateway apparatus 110. Therefore, the transmission of the Create UPSession Request message and the Create UP Session Response messagebetween the SGSN-U 93 and the GGSN-U 94 is not performed as transmissionof packet data, but is performed as internal processes in the apparatus.Arrows indicated by broken lines in the steps S76 and S77 indicate thatthey are performed as internal processes in the apparatus. In this way,a tunnel can be formed between the SGSN-U 93 and the GGSN-U 94.

Next, the SGSN-U 93 transmits a Create UP Session Response messageincluding SGSN-U information (F-TEID) and GGSN-U information (F-TEID) tothe SGSN-C 91 as a response message to the Create UP Session Requestmessage transmitted in the step S75 (S78). Note that a protocol otherthan the GTP protocol may be used for the above-described Create UPSession Request message and the Create UP Session Response message.Next, the SGSN-C 91 transmits a Create PDP Context Request message tothe GGSN-C 92 by using a GTPv1 protocol (S79).

Next, the GGSN-C 92 transmits a Create PDP Context Response message tothe SGSN-C 91 as a response message to the Create PDP Context Requestmessage transmitted in the step S79 (S80). An Attach process in the stepS80 and subsequent steps is similar to an Attach process specified inNon-patent Literature 1 and hence a detailed description thereof isomitted.

Further, in FIG. 14, although the SGSN-C 91 sets the RAI in the DNSQuery message and transmits the DNS Query message in the step S74, itmay set only the APN designated by the UE 50 without setting the RAI. Insuch a case, the DNS 46 transmits a response message in which the GGSN-C92 associated only with the APN is set to the SGSN-C 91. The SGSN-C 91receives the response message in which the GGSN-C 92 is set. However,depending on the configuration, the SGSN-C 91 may be able to determinewhether there is a gateway apparatus in which the SGSN-U and the GGSN-Uare integrally configured.

Further, even when the SGSN-C 91 cannot determine whether there is agateway apparatus in which the SGSN-U and the GGSN-U are integrallyconfigured, the SGSN-C 91 transmits the Create PDP Context Requestmessage in which the Collocated flag is set to the GGSN-C 92. That is,when the SGSN-C 91 sets only the APN in the DNS Query message withoutsetting the RAI and transmits the DNS Query message to the DNS 46, theSGSN-C 91 transmits the Create PDP Context Request message in which theCollocated flag is set to the GGSN-C 92 without determining whether ornot there is the gateway apparatus. When there is a gateway apparatus inwhich the SGSN-U and the GGSN-U associated with the APN and the RAIincluded in the Create PDP Context Request message are integrallyconfigured, the GGSN-C 92 performs processes similar to those in thestep S80 and subsequent steps shown in FIG. 14. When there is no gatewayapparatus in which the SGSN-U and the GGSN-U associated with the APN andthe RAI included in the Create PDP Context Request message areintegrally configured, the GGSN-C 92 may transmit an error message tothe SGSN-C 91.

Seventh Embodiment

Next, a modified example of the communication system shown in FIG. 4 isdescribed with reference to FIG. 15. In FIG. 15, a UTRAN 90 is used inplace of the eNB 48 in FIG. 4, and an SGSN 130 is used in place of theMME 44. Note that in the SGSN 130, an SGSN-U and an SGSN-C are formed asan integrated apparatus. As described above, even when an SGSN specifiedin the 3GPP is used as a control apparatus, advantageous effects similarto those in the second embodiment can be obtained.

Next, configuration examples of the MME 44, the SGW-C 30, and the PGW-C40 described in the above-described plurality of embodiments aredescribed hereinafter.

FIG. 16 is a block diagram showing a configuration example of the MME40, the SGW-C 30, and the PGW-C 40 (hereinafter referred to as the MME40 and the like). As shown in FIG. 16, the MME 40 includes a networkinterface 1201, a processor 1202, and a memory 1203. The networkinterface 1201 is used for communication with a network node. Thenetwork interface 1201 may include, for example, a network interfacecard (NIC) in conformity with IEEE 802.3 series.

The processor 1202 performs processes performed by the respective MME 40explained with reference to the sequence diagrams and the flowcharts inthe above-described embodiments by loading a software module from thememory 1203 and executing the loaded software module. The processor 1202may be, for example, a microprocessor, an MPU, or a CPU. The processor1202 may include a plurality of processors.

The memory 1203 is formed by a combination of a volatile memory and anonvolatile memory. The memory 1203 may include a storage disposed apartfrom the processor 1202. In this case, the processor 1202 may access thememory 1203 through an I/O interface (not shown).

In the example shown in FIG. 16, the memory 1203 is used to store agroup of software modules. The processor 1202 can perform processesperformed by the MME 40 explained in the above-described embodiments byloading the group of software modules from the memory 1203 and executingthe loaded software modules.

As explained above with reference to FIG. 16, each of the radio relayapparatuses in the above-described embodiments executes one or aplurality of programs including a group of instructions to cause acomputer to perform an algorithm explained above with reference to thedrawings.

In the above-described examples, the program can be stored and providedto a computer using any type of non-transitory computer readable media.Non-transitory computer readable media include any type of tangiblestorage media. Examples of non-transitory computer readable mediainclude magnetic storage media (such as floppy disks, magnetic tapes,hard disk drives, etc.), optical magnetic storage media (e.g.,magneto-optical disks), CD-ROM (compact disc read only memory), CD-R(compact disc recordable), CD-R/W (compact disc rewritable), andsemiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM(erasable PROM), flash ROM, RAM (random access memory), etc.). Theprogram may be provided to a computer using any type of transitorycomputer readable media. Examples of transitory computer readable mediainclude electric signals, optical signals, and electromagnetic waves.Transitory computer readable media can provide the program to a computervia a wired communication line (e.g., electric wires, and opticalfibers) or a wireless communication line.

Note that the present disclosure is not limited to the above-describedembodiments and can be modified as appropriate without departing fromthe spirit and scope of the present disclosure. Further, the presentdisclosure may be carried out by combining above-described embodimentsas appropriate with one another.

Although the present invention is explained above with reference toembodiments, the present invention is not limited to the above-describedembodiments. Various modifications that can be understood by thoseskilled in the art can be made to the configuration and details of thepresent invention within the scope of the invention.

This application is based upon and claims the benefit of priority fromJapanese patent applications No. 2016-006030, filed on Jan. 15, 2016,the disclosure of which is incorporated herein in its entirety byreference.

The whole or part of the embodiments disclosed above can be describedas, but not limited to, the following Supplementary notes.

(Supplementary Note 1)

A communication system comprising:

a user plane PGW (Packet Data Network Gateway) configured to connect toa PDN (Packet Data Network);

a user plane SGW (Serving Gateway) configured to relay user plane databetween the user plane PGW and a base station;

a control plane SGW configured to manage the user plane SGW; and

a control apparatus configured to, when a plurality of connections areestablished for a communication terminal, transmit informationindicating that the user plane SGW and the user plane PGW can beintegrally configured to the control plane SGW for each of the pluralityof connections.

(Supplementary Note 2)

The communication system described in Supplementary note 1, wherein

when the control plane SGW receives the information indicating that theuser plane SGW and the user plane PGW can be integrally configured fromthe control apparatus,

the control plane SGW selects a first gateway apparatus in which a firstuser plane PGW and a first user plane SGW are integrally configured asan apparatus that establishes a connection between the apparatus and thebase station for transmitting user data related to a first APN, thefirst user plane PGW being configured to connect to a PDN correspondingto the first APN, the first user plane SGW being configured to relayuser plane data transmitted between the first user plane PGW and thebase station, and

the control plane SGW selects a second gateway apparatus in which asecond user plane PGW and a second user plane SGW are integrallyconfigured as an apparatus that establishes a connection between theapparatus and the base station for transmitting user data related to asecond APN, the second user plane PGW being configured to connect to aPDN corresponding to the second APN, the second user plane SGW beingconfigured to relay user plane data transmitted between the second userplane PGW and the base station.

(Supplementary Note 3)

The communication system described in Supplementary note 2, furthercomprising a control plane PGW configured to control the first andsecond user plane PGWs, wherein

the control plane SGW transmits identification information of the firstuser plane PGW constituting the first gateway apparatus andidentification information of the second user plane PGW constituting thesecond gateway apparatus to the control plane PGW.

(Supplementary Note 4)

The communication system described in Supplementary note 1, furthercomprising a control plane PGW configured to control the first andsecond user plane PGWs, wherein

the control plane SGW transmits information indicating that the userplane SGW and the user plane PGW can be integrally configured to thecontrol plane PGW, and

when the control plane PGW receives the information indicating that theuser plane SGW and the user plane PGW can be integrally configured fromthe control plane SGW,

the control plane SGW selects a first gateway apparatus in which a firstuser plane PGW and a first user plane SGW are integrally configured asan apparatus that establishes a connection between the apparatus and thebase station for enabling the communication terminal to transmit userdata related to a first APN, the first user plane PGW being configuredto connect to a PDN corresponding to the first APN, the first user planeSGW being configured to relay user plane data transmitted between thefirst user plane PGW and the base station, and

the control plane SGW selects a second gateway apparatus in which asecond user plane PGW and a second user plane SGW are integrallyconfigured as an apparatus that establishes a connection between theapparatus and the base station for enabling the communication terminalto transmit user data related to a second APN, the second user plane PGWbeing configured to connect to a PDN corresponding to the second APN,the second user plane SGW being configured to relay user plane datatransmitted between the second user plane PGW and the base station.

(Supplementary Note 5)

The communication system described in Supplementary note 4, wherein thecontrol plane PGW transmit identification information of the first userplane SGW constituting the first gateway apparatus and identificationinformation of the second user plane SGW constituting the second gatewayapparatus to the control plane SGW.

(Supplementary Note 6)

The communication system described in any one of Supplementary notes 1to 5, further comprising a management apparatus configured to: managelocation information related to a base station and a user plane SGW inassociation with each other; manage an APN and a user plane PGW inassociation with each other; and manage the user plane SGW and the userplane PGW, and a gateway apparatus formed of the user plane SGW and theuser plane PGW in association with each other, wherein

the control apparatus designates the location information and the APN,and determines whether or not there is a gateway apparatus formed of auser plane SGW associated with the designated location information and auser plane PGW associated with the designated APN by using themanagement apparatus.

(Supplementary Note 7)

A communication system comprising:

a user plane GGSN (Gateway GPRS Support Node) configured to connect to aPDN (Packet Data Network);

a user plane SGSN (Serving GPRS Support Node) configured to relay userplane data between the user plane GGSN and a base station;

a control plane SGSN configured to manage the user plane SGSN; and

a control apparatus configured to, when a plurality of connections areestablished for a communication terminal, transmit informationindicating that the user plane SGSN and the user plane GGSN can beintegrally configured to the control plane SGSN for each of theplurality of connections.

(Supplementary Note 8)

A control apparatus comprising:

a selection unit configured to select a control plane SGW for acommunication terminal when a plurality of connections are established;and

a communication unit configured to transmit information indicating thata user plane PGW and a user plane SGW can be integrally configured tothe control plane SGW for each of the plurality of connections, the userplane PGW being configured to connect to a PDN, the user plane SGW beingconfigured to relay user plane data between the user plane PGW and abase station.

(Supplementary Note 9)

A control apparatus comprising:

a selection unit configured to select a control plane SGSN for acommunication terminal when a plurality of connections are established;and

a communication unit configured to transmit information indicating thata user plane GGSN and a user plane SGSN can be integrally configured tothe control plane SGSN for each of the plurality of connections, theuser plane GGSN being configured to connect to a PDN, the user planeSGSN being configured to relay user plane data between the user planeGGSN and a base station.

(Supplementary Note 10)

A communication method comprising:

selecting a control plane SGW for a communication terminal when aplurality of connections are established; and

transmitting information indicating that a user plane PGW and a userplane SGW can be integrally configured to the control plane SGW for eachof the plurality of connections, the user plane PGW being configured toconnect to a PDN, the user plane SGW being configured to relay userplane data between the user plane PGW and a base station.

(Supplementary Note 11)

A communication method comprising:

selecting a control plane SGSN for a communication terminal when aplurality of connections are established; and

transmitting information indicating that a user plane GGSN and a userplane SGSN can be integrally configured to the control plane SGSN foreach of the plurality of connections, the user plane GGSN beingconfigured to connect to a PDN, the user plane SGSN being configured torelay user plane data between the user plane GGSN and a base station.

(Supplementary Note 12)

A program for causing a computer to:

select a control plane SGW for a communication terminal when a pluralityof connections are established; and

transmit information indicating that a user plane PGW and a user planeSGW can be integrally configured to the control plane SGW for each ofthe plurality of connections, the user plane PGW being configured toconnect to a PDN, the user plane SGW being configured to relay userplane data between the user plane PGW and a base station.

(Supplementary Note 13)

A program for causing a computer to:

select a control plane SGSN for a communication terminal when aplurality of connections are established; and

transmit information indicating that a user plane GGSN and a user planeSGSN can be integrally configured to the control plane SGSN for each ofthe plurality of connections, the user plane GGSN being configured toconnect to a PDN, the user plane SGSN being configured to relay userplane data between the user plane GGSN and a base station.

REFERENCE SIGNS LIST

-   1 PDN-   2 PDN-   10 GATEWAY APPARATUS-   12 SGW-U-   14 PGW-U-   20 GATEWAY APPARATUS-   22 SGW-U-   24 PGW-U-   30 SGW-C-   32 CONTROL APPARATUS-   34 BASE STATION-   36 COMMUNICATION TERMINAL-   40 PGW-C-   41 PGW-C-   42 PCRF-   43 PCRF-   44 MME-   45 HSS-   46 DNS-   48 ENB-   50 UE-   61 COMMUNICATION UNIT-   62 SELECTION UNIT-   63 DETERMINATION UNIT-   71 COMMUNICATION UNIT-   72 INSTRUCTION INFORMATION DETERMINATION UNIT-   81 COMMUNICATION UNIT-   82 INSTRUCTION INFORMATION DETERMINATION UNIT-   83 APPARATUS SELECTION UNIT-   90 UTRAN-   91 SGSN-C-   92 GGSN-C-   93 SGSN-U-   94 GGSN-U-   95 SGSN-U-   96 GGSN-U-   97 GGSN-C-   101 PDN-   102 PDN-   110 GATEWAY APPARATUS-   120 GATEWAY APPARATUS-   130 SGSN

The invention claimed is:
 1. A communication method for a mobilecommunication system, the communication method comprising: selecting, bya Mobility Management Entity (MME) or a Serving GPRS Support Node (SGSN)that performs mobility management of a communication terminal (UE), aServing Gateway for control plane (SGW-C) and a Packet Data NetworkGateway for control plane (PGW-C) that process control plane datarelated to the UE; sending, by the MME or the SGSN, a Create SessionRequest message including an indication flag to the SGW-C and the PGW-C,wherein the indication flag indicates that a Serving Gateway for userplane (SGW-U) and a Packet Data Network Gateway for user plane (PGW-U)are combined; and selecting, by the SGW-C and the PGW-C, the combinedSGW-U and PGW-U that processes user plane data related to the UE, basedon the indication flag included in the Create Session Request message.2. A mobile communication system comprising: a Mobility ManagementEntity (MME) or a Serving GPRS Support Node (SGSN) configured to performmobility management of a communication terminal (UE); a Serving Gatewayfor control plane (SGW-C) configured to process control plane datarelated to the UE; a Serving Gateway for user plane (SGW-U) configuredto process user plane data related to the UE; a Packet Data NetworkGateway for control plane (PGW-C) configured to process control planedata related to the UE; and a Packet Data Network Gateway for user plane(PGW-U) configured to process user plane data related to the UE, whereinthe MME or the SGSN selects the SGW-C and the PGW-C, wherein the MME orthe SGSN sends a Create Session Request message including an indicationflag to the SGW-C and the PGW-C, wherein the indication flag indicatesthat the SGW-U and the PGW-U are combined, and wherein the SGW-C andPGW-C select the combined SGW-U and PGW-U, based on the indication flagincluded in the Create Session Request message.
 3. A Mobility ManagementEntity (MME) apparatus, comprising: a processor that: performs mobilitymanagement of a communication terminal (UE); and selects a ServingGateway for control plane (SGW-C) and a Packet Data Network Gateway forcontrol plane (PGW-C) that process control plane data related to the UE;and a transmitter configured to send a Create Session Request messageincluding an indication flag, which indicates that a Serving Gateway foruser plane (SGW-U) and a Packet Data Network Gateway for user plane(PGW-U) are combined, to the SGW-C and the PGW-C, wherein the indicationflag is used for selecting the combined SGW-U and PGW-U that processesuser plane data related to the UE by the SGW-C and the PGW-C.
 4. The MMEapparatus according to claim 3, further comprising: a receiverconfigured to receive a Create Session Response message from the SGW-Cand the PGW-C.
 5. A method for a gateway comprising: processing controlplane data related to a communication terminal (UE); receiving a CreateSession Request message including an indication flag from a MobilityManagement Entity (MME) or a Serving GPRS Support Node (SGSN), whereinthe indication flag indicates that a Serving Gateway for user plane(SGW-U) and a Packet Data Network Gateway for user plane (PGW-U) arecombined; and selecting the combined SGW-U and PGW-U that processes userplane data related to the UE based on the indication flag included inthe Create Session Request message.